The present invention is directed to a process and apparatus for determining the volumetric contents of large size silos.
It is known to store grains and similar granular products in large silos. For example, sugar is stored in silo vessels something of the size of 10 stores tall (85 feet) with a base approximately 22 foot diameter. Similar silos are used to store grain, chemical compositions or other powder and highly granular materials. Because of the size of the silos in which the material is stored, it is virtually impossible to determine readily the depth to which the material fills the silo, that is, the volume of materials actually contained in the silo. This problem is exacerbated by the fact that highly granular and powdery materials produce a great deal of dust which prevents clear visual determination of the depth of the material. Another problem in determining such volume of material is the fact that the upper surface is not uniform, nor is it constant and therefore even if one was capable of visually determining the height of the material in the silo, it would not be an accurate indication.
At the present time the method used to determine the depth to which a silo of this type is filled is for a person to climb the 10 stories to the top of the silo, which is itself a dangerous task since such silos are freestanding, and once having reached the top of the silo to drop a plumb consisting of a heavy rock or similar stone tethered at the end of a long rope until it comes to rest on the upper surface of the material in the silo. This technique, similar to that used by Samuel Clemens in his role as riverboat captain to plumb the depths of the Mississippi, is just as ancient in its approach as it is inaccurate. Notwithstanding the fact that it is common to make such a measurement at least once every four hours, the actual volume of the material in the silo is never truly determined. This is a very big problem because as the silos are being emptied, from the bottom, in order to process the powdered material, they are being refilled from the top. Any misadjustment in the ratio of output to input can have disastrous results, particularly since most powdered materials in such high quantities present both not only a health hazard, but also a fire and explosion hazard from the dust created and by any possible overflow.
It is therefore an object of the present invention to provide a system for determining the contents of a large size silo which does not require manual measurement.
It is a further object of the present invention to provide a system for the measurement of powdered or granular material in large size silos which can be made automatically and at regular and fixed intervals, or even when the interval is desired at a selected time.
It is an important aspect of the present invention to provide a system of the type described in which the dangers inherent from a health point of view, as well as from a physical explosive and fire hazard, are eliminated.